Various techniques have been used to monitor wounds, ulcers, sores, lesions, tumours etc. (herein referred to collectively as “wounds”) both within hospitals and outside hospitals (e.g. domiciliary based care, primary care facilities etc.). Typically these wounds are concave and up to about 250 millimeters across. Manual techniques are typically labour-intensive and require examination and contact by skilled personnel. Such measurements may be inaccurate and there may be significant variation between measurements made by different personnel. Further, these approaches may not preserve any visual record for review by an expert or for subsequent comparison.
A number of techniques for the automated monitoring of wounds have been proposed; see for example U.S. Pat. No. 6,101,408, U.S. Pat. No. 6,873,340, U.S. Pat. No. 4,535,782 and U.S. Pat. No. 5,967,979. A common approach is to place a reference object next to the wound and determine the size of the wound utilising the scale of the reference object. It is often undesirable to place a reference object near to a wound and this requires an additional cumbersome step for a user and risks contamination of the wound. Further, when the target is not in the plane of the wound, or if the wound is not planar, there will be errors in any area calculation.
WO 2006/078902 discloses a system in which the scale of a captured image is determined using a laser triangulation sensor. The distance of the camera from a patient's skin is determined using the position of a laser spot in the image. Only a single laser spot is used and the laser is used only in a simple distance measurement.
Systems utilising stereoscopic vision and automated boundary determination are known but they are expensive, complex, bulky and require significant computational power. Further, automated identfication of the boundary of a wound may be inaccurate and variable. U.S. Pat. No. 6,567,682 and US2005/0084176 use stereoscopic techniques and automated wound boundary determination requiring intensive processing and bulky equipment.
Other systems, such as that described in US2004/0136579, require the camera always to be positioned with a guide against the patient's skin. While this consistently positions the camera a desired distance from the surface to be photographed and therefore sets the scale of the image, it is unwieldy and requires undesirable contact with the skin, risking contamination of the wound.
US2005/0027567 discloses a system in which a medical professional may enter patient information into a portable computing device. A nurse may also photograph the patient's wounds, these photographs becoming part of the patient's record. However, use of this image data is limited and the computing device is effectively used simply to allow notes to be taken.
It is an object of the invention to provide a simple, inexpensive and repeatable method that does not require a scale reference object to be employed and that may be performed at remote locations or to at least provide the public with a useful choice. It is a further object of the invention to provide an apparatus that is simple, portable, inexpensive and easy to use or which at least provides the public with a useful choice.